运行冒烟测试，但尝试创建4个删除操作时出现错误

Question

我正在关注赛普拉斯的tutorial，我们正在测试“待办事项”应用程序。我创建的测试应该从我创建的db.json文件中删除所有项目，添加待办事项，最后删除所有四个项目。我在每次删除操作后添加了一个cy.wait。 但是，出现以下错误：

Assert: expected [<li>, 3 more...]
not to exist in DOM

我想知道是否有人知道此错误的含义或问题所在？这是我第一次使用赛普拉斯。

describe('Smoke tests', () => {
        beforeEach(() => {
            cy.request('GET', '/api/todos')
              .its('body') 
              .each(todo => cy.request('DELETE', `/api/todos/${todo.id}`))
        })
        context('With new todos', () => {
            it.only('Save new todos', () => {
                const items = [
                    {text: 'Buy Milk', expectedLength: 1},
                    {text: 'Buy Eggs', expectedLength: 2},
                    {text: 'Buy bread', expectedLength: 3}
                ]
              cy.visit('/')
              cy.server()
              cy.route('POST', '/api/todos')
                  .as('create')  
              cy.wrap(items)
                .each(todo => {
                cy.focused()
                   .type('todo.text')
                   .type('{enter}')       
                cy.wait('@create')   
                cy.get('.todo-list li')
                   .should('have.length', todo.expectedLength)
                })  
            })
            context('With active todos', () => {
                beforeEach(() => {
                        cy.fixture('todos')
                           .each(todo => {  
                               const newTodo = Cypress._.merge(todo, {isComplete: false})
                               cy.request('POST', '/api/todos', newTodo)
                           })
                           cy.visit('/')
                })
                it('Loads existing data from DB', () => {
                    cy.get('.todo-list li')
                       .should('have.length', 4)
                })
                it.only('Deletes todos', () => {
                    cy.server()
                    cy.route('DELETE', '/api/todos/*')
                       .as('delete')
      
                    cy.get('.todo-list li')
                       .each($el => {
                            cy.wrap($el)
                              .find('.destroy') 
                              .invoke('show')
                              .click()
                                
                              cy.wait('@delete')
                       }) 
                       .should('not.exist')  
                })
            })
        })
    })